1. Field of the Invention
This invention relates generally to methods and devices for use in performing pulmonary procedures and, more particularly, to devices and procedures for treating lung diseases.
2. Description of the Related Art
Certain pulmonary diseases, such as emphysema, reduce the ability of one or both lungs to fully expel air during the exhalation phase of the breathing cycle. Such diseases are accompanied by chronic or recurrent obstruction to air flow within the lung. One of the effects of such diseases is that the diseased lung tissue is less elastic than healthy lung tissue, which is one factor that prevents full exhalation of air. During breathing, the diseased portion of the lung does not fully recoil due to the diseased (e.g., emphysematic) lung tissue being less elastic than healthy tissue. Consequently, the diseased lung tissue exerts a relatively low driving force, which results in the diseased lung expelling less air volume than a healthy lung.
The problem is further compounded by the diseased, less elastic tissue that surrounds the very narrow airways that lead to the alveoli, which are the air sacs where oxygen-carbon dioxide exchange occurs. The diseased tissue has less tone than healthy tissue and is typically unable to maintain the narrow airways open until the end of the exhalation cycle. This traps air in the lungs and exacerbates the already-inefficient breathing cycle. The trapped air causes the tissue to become hyper-expanded and no longer able to effect efficient oxygen-carbon dioxide exchange.
In addition, hyper-expanded, diseased lung tissue occupies more of the pleural space than healthy lung tissue. In most cases, a portion of the lung is diseased while the remaining part is relatively healthy and, therefore, still able to efficiently carry out oxygen exchange. By taking up more of the pleural space, the hyper-expanded lung tissue reduces the amount of space available to accommodate the healthy, functioning lung tissue. As a result, the hyper-expanded lung tissue causes inefficient breathing due to its own reduced functionality and because it adversely affects the functionality of adjacent healthy tissue.
Lung reduction surgery is a conventional method of treating emphysema. However, such a conventional surgical approach is relatively traumatic and invasive, and, like most surgical procedures, is not a viable option for all patients.
Some recently proposed treatments for emphysema or other lung ailments include the use of devices that isolate a diseased region of the lung in order to modify the air flow to the targeted lung region or to achieve volume reduction or collapse of the targeted lung region. According to such treatments, one or more bronchial isolation devices are implanted in airways feeding the targeted region of the lung. The bronchial isolation device regulates fluid flow through the bronchial passageway in which the bronchial isolation device is implanted. The bronchial isolation devices can be, for example, one-way valves that allow flow in the exhalation direction only, occluders or plugs that prevent flow in either direction, or two-way valves that control flow in both directions.
The following references describe exemplary bronchial isolation devices: U.S. Pat. No. 5,954,766 entitled “Body Fluid Flow Control Device”; U.S. patent application Ser. No. 09/797,910, entitled “Methods and Devices for Use in Performing Pulmonary Procedures”; and U.S. patent application Ser. No. 10/270,792, entitled “Bronchial Flow Control Devices and Methods of Use”. The foregoing references are all incorporated by reference in their entirety and are all assigned to Emphasys Medical, Inc., the assignee of the instant application.
The bronchial isolation device can be implanted in a target bronchial passageway using a delivery catheter that is placed through the trachea (via the mouth or the nasal cavities) and to the target location in the bronchial passageway. It would be advantageous to develop improved methods and devices for delivering bronchial isolation devices into the lung of a patient.